Cal 31 Propeller Question - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 12 Old 4 Weeks Ago Thread Starter
Member
 
Join Date: Jan 2014
Posts: 57
Thanks: 20
Thanked 5 Times in 5 Posts
Rep Power: 2
 
Cal 31 Propeller Question

After just completing a 500 mile inland motoring trip and having had time to digest/study my observations, I think my propeller is too small. My best speed was 4.5 miles per hour (no current) and my fuel use seemed very low (0.35 to 0.4 gal/hr at high rpm) compared to what the performance charts say it should be. I don't have a tachometer so I am not sure what the actual rpm was, but I was pushing it pretty hard. I also could not motor against 2-3 foot waves and 20 mph wind in Appalachacola bay.

I am now back home in Tennessee and the boat is in Florida. If I had come to this conclusion while at the boat I would have measured the existing prop to compare with prop size recommendations I am now getting.

I have a Universal 5416 (16 hp) diesel with 2:1 gear reduction, which was what came with the boat when built. The prop vendors are suggesting a 14 by 9 three-blade.

What props are being run by other sailers with similiar boats and engines? My loaded displacement is about 11,000 lbs.
Cal31Windchaser is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 12 Old 2 Weeks Ago
Senior Member
 
JimsCAL's Avatar
 
Join Date: May 2007
Location: Glen Cove, NY
Posts: 2,771
Thanks: 2
Thanked 68 Times in 63 Posts
Rep Power: 9
 
Re: Cal 31 Propeller Question

That's pretty poor motoring performance. The low fuel usage indicates the motor is running at a low power, probably due to a poorly sized prop. You say you were pushing it pretty hard, but the fuel usage says something different. You should have no trouble motoring at 6+ knots with that engine in that boat. A friend had a Cal 31 with the 5416 and never complained about powering issues.

What is the diameter and pitch of your current prop? While a fixed 3-bladed would certainly maximize powering, it would reduce your speed under sail, especially in light air. A fixed 2-blade, or even a 2-bladed folding or feathering prop if properly sized, should work just fine.
JimsCAL is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to JimsCAL For This Useful Post:
Cal31Windchaser (2 Weeks Ago)
post #3 of 12 Old 2 Weeks Ago
Senior Member
 
overbored's Avatar
 
Join Date: Oct 2010
Location: Dana Point, Ca
Posts: 1,165
Thanks: 1
Thanked 60 Times in 60 Posts
Rep Power: 5
 
Re: Cal 31 Propeller Question

Is the bottom clean? you need to know the rpm? you need to know that the engine is running at max power before you can size a prop. how do you know you were pushing it hard was there a lot of black smoke. your fuel flow says you are not running it hard. what speed do you get at full throttle?

"FULL TILT II" 2011 BENETEAU FIRST 30
"FULL TILT" SOVEREL 33
"GOLD RUSH" PRINDLE 16
overbored is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to overbored For This Useful Post:
Cal31Windchaser (2 Weeks Ago)
post #4 of 12 Old 2 Weeks Ago Thread Starter
Member
 
Join Date: Jan 2014
Posts: 57
Thanks: 20
Thanked 5 Times in 5 Posts
Rep Power: 2
 
Re: Cal 31 Propeller Question

Thanks everyone for the responses. I did a new bottom job just before making the trip...its clean. Don't have a tachometer, but throttle was pushed to the stops and no black smoke. I am going back down to Carrabelle, FL (I live in Tennessee) next week and will measure the prop while there. Will be able to report that in a week or so.

Any idea what size props are being used on a Universal 5416 with a 31 foot boat? The Cal is not very heavy (9360 lbs). However, I estimate the loaded weight was around 11,000 lbs.

Looks like i can buy a used prop at Minney's in California and have employed several online prop sizing calculators to narrow down the selection. If they will take returns, I might buy several sizes and compare performance. Have asked for one of those optical tachometers for my birthday to better understand what is happening, per Overboard's input.

Again, thanks!
Cal31Windchaser is offline  
Quote Quick Reply Share with Facebook
post #5 of 12 Old 2 Weeks Ago
Just another Moderator
 
Faster's Avatar
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 16,518
Thanks: 104
Thanked 309 Times in 299 Posts
Rep Power: 10
     
Re: Cal 31 Propeller Question

Certainly sounds like a pitch issue.. dirty bottom or fouled prop would 'load' the engine and in any case you know that's not the situation.

You say you've used the various prop calculators.. what was the average recommendation?

Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Faster is online now  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to Faster For This Useful Post:
Cal31Windchaser (2 Weeks Ago)
post #6 of 12 Old 2 Weeks Ago
Senior Member
 
JimsCAL's Avatar
 
Join Date: May 2007
Location: Glen Cove, NY
Posts: 2,771
Thanks: 2
Thanked 68 Times in 63 Posts
Rep Power: 9
 
Re: Cal 31 Propeller Question

The pitch and diameter should be stamped on the prop. You can measure the diameter but its not real easy to measure the pitch accurately.

Checking the RPM somehow is worthwhile. You say you had the throttles pushed all the way, but it could just be a throttle cable adjustment. Ideally you should be hitting rated engine RPM when the engine is at maximum power.
JimsCAL is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to JimsCAL For This Useful Post:
Cal31Windchaser (2 Weeks Ago)
post #7 of 12 Old 2 Weeks Ago Thread Starter
Member
 
Join Date: Jan 2014
Posts: 57
Thanks: 20
Thanked 5 Times in 5 Posts
Rep Power: 2
 
Re: Cal 31 Propeller Question

Faster, Deep Blue Yacht Supply is recommending a 15 by 10, 3-blade Michigan Wheel MP3 or 15 by 11, 3-blade Michigan Wheel Sailor 3. The VicProp calculator came up with a 14 by 8, 3-blade. Another spreadsheet calculator I found through one of the forums computed a 14 by 9 but came up with same size as VicProp when I changed the cruise speed to the same value (80% of WOT) used by VicProp.

JimsCal, I wondered the same thing. If my cable was way out of adjustment, I might have not been close to WOT. One thing I did observe was that the engine temperature went up to 185 deg F when the throttle was pushed all the way, which led me to believe I was working somewhere near to WOT.
Cal31Windchaser is offline  
Quote Quick Reply Share with Facebook
post #8 of 12 Old 2 Weeks Ago
Senior Member
 
overbored's Avatar
 
Join Date: Oct 2010
Location: Dana Point, Ca
Posts: 1,165
Thanks: 1
Thanked 60 Times in 60 Posts
Rep Power: 5
 
Re: Cal 31 Propeller Question

you can get a tiny tach for diesel for $95 it may not be the prop, it could be the engine is not putting out the power. filter clog, injectors bad, valves not adjusted., injection timing
Design Technology, Inc., Home of the Tiny-Tach - Diesel Tiny-Tach Tachometer

"FULL TILT II" 2011 BENETEAU FIRST 30
"FULL TILT" SOVEREL 33
"GOLD RUSH" PRINDLE 16
overbored is offline  
Quote Quick Reply Share with Facebook
post #9 of 12 Old 2 Weeks Ago Thread Starter
Member
 
Join Date: Jan 2014
Posts: 57
Thanks: 20
Thanked 5 Times in 5 Posts
Rep Power: 2
 
Re: Cal 31 Propeller Question

Does the TinyTach get its input signal from the alternator AC output or does it somehow connect mechanically? I looked at the site but it wasn't clear on this. I was thinking of getting a cheap optical tach for now to do the rpm check and then buy a permanent unit later.
Cal31Windchaser is offline  
Quote Quick Reply Share with Facebook
post #10 of 12 Old 2 Weeks Ago
Senior Member
 
overbored's Avatar
 
Join Date: Oct 2010
Location: Dana Point, Ca
Posts: 1,165
Thanks: 1
Thanked 60 Times in 60 Posts
Rep Power: 5
 
Re: Cal 31 Propeller Question

Quote:
Originally Posted by Cal31Windchaser View Post
Does the TinyTach get its input signal from the alternator AC output or does it somehow connect mechanically? I looked at the site but it wasn't clear on this. I was thinking of getting a cheap optical tach for now to do the rpm check and then buy a permanent unit later.
the one I had used a pickup mounted near the belt pulley and a piece of magnetic tape on the pulley

"FULL TILT II" 2011 BENETEAU FIRST 30
"FULL TILT" SOVEREL 33
"GOLD RUSH" PRINDLE 16
overbored is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to overbored For This Useful Post:
Cal31Windchaser (2 Weeks Ago)
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Propeller question grinfax Gear & Maintenance 15 05-24-2012 03:54 PM
Propeller Sizing Question - Help! PHN Diesel 10 10-18-2011 11:10 AM
Propeller question pegasus1457 Gear & Maintenance 3 11-15-2010 01:38 PM
Outboard Propeller Question Quickstep192 Gear & Maintenance 2 03-03-2009 06:56 AM
Propeller Question Scurvy_Dog General Discussion (sailing related) 4 02-19-2003 04:59 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome